In colouring, these superb birds show what endless possibilities are open to the artist who confines himself to black and white and their combinations.

There is in the flight of terns a poetry of motion over which no one with an eye for the beautiful can fail to wax enthusiastic. The popular name for terns—sea-swallows—is a tribute to their wing power. They are all designed upon a common plan. Length and slimness characterise every part of their anatomy, save the legs, which are very short. Terns rarely walk; nearly all their movements are aerial.

The terns that commonly frequent the rivers of Upper India are of three species—the black-bellied tern (Sterna melanogaster), the Indian river tern (S. seena) with its deeply forked tail, and the whiskered tern (Hydrochelidon hybrida), a study in pale grey. These, when not resting on a sandbank, are dashing through the air without effort, ever and anon dropping on to the water to pick something from off the surface, or plunging in after a fish. Allied to the terns, and found along with them, are the Indian skimmers (Rynchope albicollis), easily recognised by their larger size and black wings.

The passing of a black crow causes some of the terns to desist from their piscatorial occupation, in order to mob the intruder. This means that there are terns’ eggs or young ones in the vicinity. Many species of birds betray the presence of their nests by displaying unusual pugnacity at the breeding season. To discover the eggs or young of the terns is not a difficult matter. It is only necessary to land upon the nearest island between which and the river bank there is a sufficient depth of water to prevent jackals fording it. If the island contain eggs or young ones, the parent birds will make a hostile demonstration by collecting overhead and flying backwards and forwards, uttering their harsh cries, and the nearer one approaches the nest the more clamorous do they become. In this manner they unwittingly inform the nest-seeker whether he is getting “hot” or “cold,” to use the expressions employed in a nursery game.

The terns which breed on islets in Indian rivers do not appear to do much incubating in the daytime. There is no need for them to do so, because the sand grows very warm under the rays of the sun. Moreover, the only foes to be feared are the crows and the kites, which the terns can keep at bay more effectually when on the wing than while sitting on the eggs. Very different is the behaviour of the sea terns, whose eggs are liable to attack by gulls and crabs. For safety’s sake the sea terns lay in large colonies, and, to use Colonel Butler’s expression, sit on their eggs “packed together as close as possible without, perhaps, actually touching one another.” He once came upon the nests of a colony of large-crested terns (Sterna bergii). The sitting birds did not leave their eggs until he was within a few yards of them. Having put them up, he retired to a little distance. “No sooner had I done so,” he writes, “than both species [i.e. the gulls and terns] began to descend in dozens to the spot where the eggs were lying. In a moment a general fight commenced, and it was at once evident that the eggs belonged to Sterna bergii, and that the gulls were carrying them off and swallowing their contents as fast as they could devour them.” River terns do not construct any nest. They deposit their eggs on the bare, dry sand. The eggs have a stone-coloured ground, sometimes suffused with pink, blotched with dark patches, those at the surface of the shell having a sepia hue, and those deeper down appearing dark greyish mauve. The eggs, although not conspicuous, may, without difficulty, be detected when lying on the sand. Their colouring would seem to be adapted to match a stony, rather than a sandy environment, but the fact that the colouring of the eggs is but imperfectly protective does not much matter when the latter lie on a sand island, to which but few predaceous creatures have access; the watchfulness of the parent birds more than compensates for the comparative conspicuousness of the eggs.

Young terns, like most other birds, are born helpless, and are then covered with a greyish down; but before the tail feathers have broken through their sheaths, and while the wing feathers are quite rudimentary, the ternlets learn to run about and swim upon the water. At this stage the little terns look like ducklings when on the water, and, as they run along the water’s edge, may easily be mistaken, at a little distance, for sandpipers.

When a young tern is surprised by some enemy, his natural instinct is to crouch down, half buried in the sand, and to remain there quite motionless until the danger has passed. The colouring of his down is such as to cause him to assimilate more closely to the sandy environment than the eggs do. If one picks up such a crouching ternlet, the bird will probably not struggle at all; it may, perhaps, peck at one’s fingers, but in nine cases out of ten will remain limp and motionless in the hand, looking as though it were dead, and if it be set upon the ground it falls all of a heap, and remains motionless in the position it assumed when dropped. If you take a young tern in your hand and lay it upon its back on the sand it makes no attempt to right itself, but remains motionless in that attitude, looking for all the world like a trussed chicken; but if you turn your back upon it, it will take to its little legs and run, with considerable speed, to the water, to which it takes just as a duck does, its feet being webbed at all stages of its existence.